Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
INF=10**18
h,w=map(int,input().split())
a=[input() for _ in range(h)]
d=[[INF for _ in range(w)]for _ in range(h)]
dx=[0,1,0,-1]
dy=[1,0,-1,0]
sx,sy=0,0
gx,gy=h-1,w-1
d[sx][sy]=1
q=deque([(sx,sy)])
while q:
  x,y=q.popleft()
  if (x,y)==(gx,gy):break
  for i in range(4):
    nx,ny=x+dx[i],y+dy[i]
    if 0<=nx<h and 0<=ny<w:
      if a[nx][ny]=='.' and d[nx][ny]==INF:
        d[nx][ny]=d[x][y]+1
        q.append((nx,ny))
if d[gx][gy]==INF:print(-1)
else:
  cnt=0
  for i in a:
    cnt+=i.count('.')
  print(cnt-d[gx][gy])